1. Field of the Invention
The present invention relates to clays and, more particularly, to a unique technique for controlling the viscosity and preventing gelling of clay slurries stored or shipped in tanks, tanks cars, and the like.
2. Description of the Prior Art
As known in the art, refined clays are sold under certain required specifications including, e.g., brightness, particle-size distribution, viscosity, and the like. Because natural variations in the properties of crude clay are common, the crude clay ore is subjected to various known processing techniques, such as fractionation, delamination, treatment with chemical additives, leaching agents, flocculants, etc. A specific example of such a process is disclosed in U.S. Pat. No. 3,371,988 to Maynard et al which issued Mar. 5, 1968. In accordance with the innovation disclosed by this patent, an aqueous clay suspension is contacted with a peptizing agent in an amount in excess of that required to maintain minimum viscosity and in an amount sufficient to effect separation of titanium impurities and to improve the brightness of the clay. Further examples of known processes for refining or treating clays are disclosed in U.S. Pat. Nos. 3,320,027 and 3,442,677.
Notwithstanding the precise process employed, e.g., the use of specific leaching agents, etc., it is common practice in the industry to ship the refined clay pigments to the ultimate user or customer as a dispersed high solids slurry thereof.